1. Field of the Invention
The present invention relates to an image forming apparatus which forms an image using toner. The present invention relates in particular to a technique for accurately grasping the states of use of the main section of the apparatus and consumables and for properly managing the apparatus.
2. Description of the Related Art
In the case of an image forming apparatus such as a printer, a copier machine and a facsimile machine which uses toner to form an image, as the apparatus is used more, the quality of an image becomes poorer owing to changes of the state of the apparatus such as a deterioration within the apparatus and a reduction of the remaining toner amount for example. There are various different ideas as for how to grasp such changes of the state of the apparatus and how to deal with these changes.
An example is an apparatus which calculates the amount of remaining toner inside the apparatus based on a count registered in a toner counter which counts the amount of toner which is consumed as an image is formed, and which then determines, from thus calculated remaining toner amount, the timing of exchanging a toner cartridge in which the toner is stored. In other words, when the calculated amount of remaining toner inside the toner cartridge drops beyond a certain level, a display of the image forming apparatus shows a message such as “Please exchange the toner cartridge.” to thereby encourage a user to exchange the toner cartridge.
In an effort to make an effective use of resources, users wish to accurately grasp the remaining toner amount and exchange a toner cartridge at a proper time, that is, when toner has been just entirely used. However, conventional toner counting techniques realize only insufficient accurate counting and have thus failed to meet this demand.
Further, among this type of apparatuses are those which form a small test image (patch image) having a predetermined image pattern and adjust their operation conditions based on the result of density detection on the patch image. It is desirable that the result of the density detection on the patch image is utilized to grasp changes of the state of the apparatus. Meanwhile, for an effective use of resources mentioned above, there is a users' demand to form images even at the expense of a deteriorated image quality to an extent tolerable. When an image is to be formed in such a situation, the result of the density detection on the patch image must be specially handled. The conventional control techniques for image forming apparatuses nonetheless have not considered such a need very much.